Full stream ahead for Lower Owens

As blizzards whipped across nearby High Sierra peaks, ecologist William Platts lifted off in a helicopter here and headed north, about 1,000 feet above a river that looked as if it were throwing a tantrum.

Beneath him, the squiggle of green was overflowing its banks, inundating a patchwork of oxbows, marshlands, forests and sagebrush. Culverts were nearly filled to capacity, and mats of dislodged tules and muck hurtled down the river.

“I really like what I see down there,” the 80-year-old Platts told the chopper pilot through the headphone radio. “But we’ll need three or four more seasonal pulses to kick-start this ecosystem into gear.”

The Lower Owens River has flooded for millenniums, but this flood was man-made, part of the most ambitious river restoration project in the West. The river mostly disappeared when the Los Angeles Aqueduct opened in 1913, but 15 months ago engineers began redirecting some aqueduct water into the channel.

The flood should flush the recently revived river of a century’s worth of cattle waste and debris, add topsoil to its flood plain and spur an awakening of riparian rhythms without harming fish populations. Eventually, a canopy forest will grow along the 62-mile river, and Inyo County officials hope the waterway will support a thriving recreation industry.

But whether the project achieves that potential will depend on three river bosses who rarely agree: the Los Angeles Department of Water and Power, Inyo County and environmentalists whose lawsuit led to a judicial order that launched the 77,657-acre project as mediation for environmental damage from DWP pumps sucking out groundwater.

Some suggest that the effort also might be affected by drought conditions, which could reduce interest in the project that runs on 55,000 cubic feet of Sierra snowmelt a year.

“If there was not enough water to go around and people were suffering, this project would be the first thing to go,” said project consultant Mark Hill, who helped develop the plan along with Platts. “It’s sacrosanct now and under a court order. But no one should think it’s set in stone. It’s not.”

Early signs, however, are hopeful. With Los Angeles Mayor Antonio Villaraigosa’s support, the DWP has pledged stewardship of the river that until December 2006 existed as a nearly dry riverbed. A few spring-fed ponds sustained fish and beavers, but the channel was mostly choked by weeds and trampled by cattle.

Now, after a year of steady flows, it has become a sinuous oasis fringed with tules, wild rose, grass and sage. By last June, groundwater had recharged and risen faster than scientists had anticipated, and some desert shrubs had died off, making way for stream-side species. Fish -- liberated from their ponds -- were already spreading throughout the river.

Beginning next year, the Lower Owens will be flooded each spring to carry cottonwood and willow seeds along for the ride. The seeds will lodge in sandbars and terraces enriched by decomposing tules and tree leaves. By late next year, ecologists expect to see foot-tall saplings along the river’s edge.

In the meantime, wildlife is moving back into the river more quickly than expected. Bobcats are its top predators, and rough-legged hawks patrol the sky. Elk and deer drink from the stream amid the din of croaking tree frogs.

On a recent weekday, biologists watched a great blue heron take flight with a brown trout in its beak. Nearby, wood ducks and rare swans glided over a patch of coffee-colored water.

Still, the rehabilitated Lower Owens ecosystem is far from balanced. It could take 15 to 20 years before the $39-million project can be declared a success -- or a failure.

The work of gathering data on wildlife, foliage and water flows has barely begun, and one of the best ways to monitor the river’s progress is by kayak.

Digging deep with his paddle at a bend in the river on a recent weekday, Hill said: “We have to be patient and work on ecological time, not political time. Some people expect to see significant change overnight. That’s not going to happen.

“Our biggest obstacles,” the consultant added, “are lawyers and amateurs.”

Things were particularly tense a week before the DWP began increasing river flows Feb. 14 to rates as high as 220 cubic feet per second.

Warnings that rising water could flood local roads -- including all-important U.S. 395 -- and destroy cattle forage triggered unease among ranchers and elected officials in financially strapped rural Inyo County. Some vowed to seek financial compensation from the DWP.

The fears were understandable because the river has offered up surprises. Normally, the water flows at 40 cubic feet per second -- about the speed of an easy stroll -- and scientists predicted it would run 2 to 4 feet deep. Instead, the current began digging out portions of riverbed 6 to 10 feet deep.

But the pulses of water pushed through the thirsty sprawl of high desert 200 miles north of Los Angeles without incident.

“Looks like it’s going to work,” third-generation cattle rancher Mark Johns, 57, said as a nearby team of ecologists recorded the depth, temperature and oxygen levels of a stretch flowing through acreage he has leased from the DWP since 1967.

“If my grandfather was still around, he’d stomp on his hat and run everyone out of here,” Johns said. “Personally, I think it’s a good project. Probably.”

Ranchers and DWP officials warily watched the man-made flooding, and separately, Sierra Club and Audubon Society activists chronicled the flood with flyovers in airplanes and stream-side inspections.

During his recent helicopter flight over the Lower Owens, ecologist Platts surveyed the miles of glistening flood plain below with a satisfied smile.

“It will be some time before the river can sustain commercial enterprises like fishing, hiking, kayaking and bird-watching concessions,” he said from the cockpit. “But average Joes like us can still have a wonderful time just as it is.”

About a week after Platts’ flight, DWP officials began slowing the flow to its usual speed, and the river has started returning to its banks. The Lower Owens River is again a collection of lazy loops and squishy meadows, flanked by the High Sierra on the west and the White and Inyo mountains on the east.

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louis.sahagun@latimes.com

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On latimes.com

A river’s rehabilitation

More photographs of the rejuvenated Lower Owens can be seen at

latimes.com/owens